Embodiments of the present invention relate to radar applications, in particular an efficient way to process radar signals obtained by at least one radar sensor, e.g., via at least one antenna. Processing radar signals in this regard in particular refers to radar signals received by a sensor or an antenna.
Several radar variants are used in cars for various applications. For example, radar can be used for blind spot detection (parking assistant, pedestrian protection, cross traffic), collision mitigation, lane change assist and adaptive cruise control. Numerous use case scenarios for radar appliances may be directed to different directions (e.g., back, side, front), varying angles (e.g., azimuth direction angle) and/or different distances (short, medium or long range). For example, an adaptive cruise control may utilize an azimuth direction angle amounting to ±18 degrees, the radar signal is emitted from the front of the car, which allows a detection range up to several hundred meters.
A radar source emits a signal and a sensor detects a returned signal. A frequency shift between the emitted signal and the detected signal (based on, e.g., a moving car emitting the radar signal) can be used to obtain information based on the reflection of the emitted signal. Front-end processing of the signal obtained by the sensor may comprise a Fast Fourier Transform (FFT), which may result in a signal spectrum, i.e. a signal distributed across the frequency. The amplitude of the signal may indicate an amount of echo, wherein a peak may represent a target that needs to be detected and used for further processing, e.g., adjust the speed of the car based on another car travelling in front.
Constant false alarm rejection (CFAR), also referred to as constant false alarm rate, is in particular known as a threshold method for FFT result analysis which may be based on a signal power. CFAR allows adapting a threshold to decide whether the FFT signal indicates a potential target. CFAR in particular considers background noise, clutter and interference. Several CFAR algorithms are known. For details, reference is made to http://en.wikipedia.org/wiki/Constant_false_alarm_rate.
CFAR algorithms are often complex and require a significant amount of time and/or resources, e.g., costly computation power. In case they need several clock cycles to provide a result, post-processing becomes delayed which results in a limited real-time (or nearly real-time) capability of the whole system.